This invention relates to a polyester feed yarn for drawtexturing, and is more particularly concerned with yarn of three different types of filaments, one being of a type which can be preferentially broken in drawtexturing to provide a spun-like textured yarn.
Direct-spinning processes in which continuous filaments are stretch-broken to produce spun yarns are well known as illustrated by Field, Jr. U.S. Pat. No. 3,487,619. Schippers U.S. Pat. No. 4,019,311 discloses melt-spinning and orienting two different polymers simultaneously to produce a yarn of filaments having different elongations at break, and then stretching the yarn to break the lower elongation filaments and produce a spun-like yarn. However, Cardinal et al. U.S. Pat. No. 3,987,614 teaches that a yarn composed of filaments differing in break elongation is not suitable for a simultaneous drawing and texturizing process, because the filament breakage occurs in the drawing zone at the beginning of the heater and the loose ends repeatedly jam the twister of the texturizing machine (e.g., the false-twist spindle). The Cardinal et al. invention is a yarn composed of two types of filaments, wherein one type has a flex abrasion resistance of less than 1500 cycles and breaks at irregular intervals due to the transverse stress applied in the texturizing zone of the machine. Example 1 discloses production of such yarn by cospinning two polymers from the same spinneret to produce a yarn of two types of filaments having elongations at break of 310 and 375 percent. The yarn was drawtextured at a draw ratio of 1:2.90, followed by interlacing of loose filament ends into the yarn. The broken ends showed a flex abrasion resistance of 350 cycles.
Lodge et al. U.S. Pat. No. 3,546,328 discloses cospinning two polyamide compositions of different color from the same spinneret to form a yarn composed of filaments of one polyamide composition, filaments of the other polyamide composition, and side-by-side bicomponent filaments of both polyamide compositions. The yarn is said to be useful in the manufacture of fabrics in which a marl effect is required. British Pat. No. 1,130,996 discloses cospinning two different polyamides to form a yarn composed of low-shrinkage filaments of one polyamide, high shrinkage filaments of the other polyamide, and side-by-side bicomponent filaments of both polyamides. The yarn is knitted into stockings and crimped with steam to provide high stretchability with good surface smoothness.
Reese U.S. Pat. No. 3,998,042 discloses preparation of mixed-shrinkage, continuous-filament, heat-bulkable yarn, composed of low shrinkage and higher shrinkage polyester filaments, by cospinning two different polymer compositions under identical conditions. The polymer used for the low-shrinkage filaments consists of about 97 to 100 mole percent ethylene terephthalate structural units and about 3 to 0 mole percent of polymer structural units which contain sulfonate groups as pendant parts of repeating units in the polymer chain. The polymer used for the higher-shrinkage filaments consists of about 85 to 95 mole percent ethylene terephthalate structural units and about 15 to 5 mole percent of other ester units forming a copolyester therewith. The patent teaches that the break elongations of filaments of a yarn to be drawn should not differ by more than 15 percentage units so that the yarn can be drawn sufficiently without breaking filaments, since incompletely drawn segments cause uneven dyeing and harsh hand in fabrics made from the yarn. The patent discloses the use of higher relative viscosity polymer for the higher-shrinkage filaments than for the low-shrinkage filaments in order to provide nearly the same break elongations in the two types of filaments and yet produce a mixed-shrinkage yarn that develops high bulk in fabrics.